This present invention relates to a tilt mechanism for use on motor vehicles. In one aspect, it relates to a tilt mechanism for pivoting a vehicle body panel relative to a vehicle chassis. In another aspect, it relates to a method of assisting a pivotal movement of a vehicle body panel relative to a vehicle chassis. In yet another aspect, it relates to a method of installing a vehicle body panel on a vehicle chassis.
Tilt mechanisms for pivoting a vehicle body panel relative to a vehicle chassis are generally known in the fields of automotive engineering and mechanism design. There have been many mechanism designs for such tilt mechanisms over the years since the creation of the automobile and possibly even as far back as the creation of horse-drawn carriages. For example, a common hinge could be used as a tilt mechanism. Also, there have been various tilt mechanism designs that incorporate a spring member to assist the opening or closing of a vehicle body panel.
However, there exists a need for improvements to these tilt mechanism designs for various reasons. For example, conventional hood hinges (e.g., car or truck hood hinges) typically have two connection points that a hood pivots about relative to a vehicle chassis and a latch to fasten the hood in a closed position. Such conventional hood hinges are typically arranged such that there is a hinge on the driver side and another hinge on the passenger side of the vehicle, where each hinge has a pivot axis that is substantially aligned with that of the other hinge. But, because the hood typically covers the engine, the conventional hood hinges may move relative to each other when the vehicle chassis twists due to heavy loading on the engine (e.g., pulling a trailer). Also under cornering loads or other dynamic loads exerted on the vehicle chassis, the chassis may twist, causing the hinges to move relative to each other. Such relative movement between the two hinges may deform the hood. Hence, there is a need for a tilt mechanism that will allow a vehicle chassis to twist under heavy engine loading or under other dynamic loads while also not deforming a vehicle body panel attached thereto.
Another example of a needed improvement to conventional tilt mechanisms for pivoting a vehicle body panel relative to a vehicle chassis is the need for a method of installing large, bulky, and/or heavy body panels on a chassis where the tilt mechanism has a spring member for biasing the body panel relative to the chassis. When a body panel is large, bulky, and/or heavy, it is often desirable to have a spring member associated with the tilt mechanism to assist the pivoting of the body panel. But, installing a tilt mechanism that has a spring member can be quite difficult. The difficulty arises in aligning the tilt mechanism and the body panel for installation on the chassis when the spring member requires a very large force or torque to bias it, especially when the body panel is large, bulky, or heavy.
Yet another example of a needed improvement to conventional tilt mechanisms for pivoting a vehicle body panel relative to a vehicle chassis is the need for an improved tilt restraint design for limiting the pivotal range of the body panel relative to the chassis.
Many of the needs outlined above are addressed by the present invention hereof. It is an object of the present invention to provide a tilt mechanism that has a single-point pivot attachment at a pivot pin to allow lateral articulation of the attached body panel about a pivot pin axis relative to the chassis to reduce or eliminate body panel deformation under heavy engine loading or under other dynamic loads that may twist the chassis.
It is another object of the present invention to provide a tilt mechanism having a torsion bar therein adapted for biasing the body panel relative to the chassis, where a vehicle body panel attached to a vehicle chassis via the tilt mechanism can pivot about the tilt mechanism relative to the chassis without loading the torsion bar over a specified angular range about the tilt mechanism, and also the torsion bar can support at least part of the body panel weight over another portion of the pivotal range about the tilt mechanism.
It is yet another object of the present invention to provide a method of installing large, bulky, and/or heavy body panels on a chassis via a tilt mechanism without loading a torsion bar within the tilt mechanism over a tolerance range of installation angles, where the torsion bar is adapted for biasing the body panel relative to the chassis.
Still another object of the present invention is to provide a tilt restraint located within the tilt mechanism for providing at least one limit on the pivotal range of the tilt mechanism.
In accordance with one aspect of the present invention, a tilt mechanism for pivoting a vehicle body panel relative to a vehicle chassis comprises a chassis bracket, a pivot pin, a support member, compliant members, hard stops, a torsion bar, hour-glass-shaped slots, pivot brackets, bearings, and a tilt restraint.
The chassis bracket is adapted for attaching to the chassis, and pivot brackets are adapted for attaching to the body panel. Hence, the body panel can be attached to the chassis via the tilt mechanism. The pivot pin is supported by and extends through the chassis bracket along a pivot pin axis of the pivot pin. The chassis bracket has a clevis structure for receiving the pivot pin. The pivot pin is adapted for supporting at least part of a vehicle body panel weight. Also, the pivot pin is adapted for providing a single-point pivot attachment of the body panel to the chassis such that the body panel can articulate about the pivot pin axis relative to the chassis. The support member pivotably connects to the chassis bracket about the pivot pin axis and within the clevis structure of the chassis bracket at a support member midpoint by the pivot pin. The support member has a tilt axis along a longitudinal extent of the support member. The support member is also adapted for supporting at least part of the body panel weight.
The compliant members are proximate to the pivot pin within the clevis structure and are attached to the chassis bracket. The compliant members are adapted for urging a substantially parallel position of the support member relative to the chassis about the pivot pin because the members are prestressed and in contact with the support member when the support member is not being pivoted about the pivot pin. The hard stops are formed on the chassis bracket for limiting a support member pivotal range of the support member about the pivot pin.
The flat rectangular-shaped torsion bar is within the support member and secured to the support member midpoint at a torsion bar midpoint. The torsion bar has a twist axis along a longitudinal extent of the torsion bar that is generally perpendicular to the pivot pin axis and substantially axially aligned with the tilt axis. The torsion bar is adapted for biasing the body panel relative to the chassis along at least an angular portion of a pivotal range about the tilt axis. Each end of the torsion bar forms a key pin.
Hour-glass-shaped slots are formed in the pivot brackets. The slots are adapted for receiving the key pins such that the pivot brackets can pivot about the tilt axis relative to the chassis bracket without loading the torsion bar over a specified angular range. Two bearings, one fixed to each of the pivot brackets, have a bearing rotation axis substantially axially aligned with the tilt axis. Each of the bearings forms a socket for receiving each end of the support member. The bearings are adapted for transferring at least part of the body panel weight from the pivot brackets to the support member while also allowing the pivot brackets to pivot about the tilt axis relative to the support member.
The tilt restraint is adapted for providing a limit on a pivot bracket rotational range of the pivot bracket about the tilt axis. The tilt restraint is located within and fixed to the support member. The tilt restraint is axially located along the tilt axis proximate to one of the ends of the support member. The tilt restraint is adapted for abutting with a surface of the torsion bar at the limit to hinder further pivoting about the tilt axis.
Important elements of the present invention are the support member, the pivot pin, the torsion bar, the hour-glass-shaped slots, and the tilt restraint. All possible embodiments will incorporate the support member. Other embodiments of the present invention may comprise various combinations of the primary elements added to the support member. For example, one embodiment may have the tilt mechanism with all of the primary elements except for the torsion bar, the hour-glass-shaped slots, and the tilt restraint, which would be a tilt mechanism with single-point pivot attachment that allows lateral articulation about the pivot pin. Another embodiment may have, for example, the tilt mechanism with all of the primary elements except for the hour-glass-shaped slots and the tilt restraint, which would be a tilt mechanism with a single-point pivot attachment and a torsion bar to bias against a moment created by the body panel weight for assisting the opening and closing of the body panel.
In accordance with a further aspect of the present invention, a method of assisting a pivotal movement of a vehicle body panel relative to a vehicle chassis comprises the steps of, first, supporting at least a portion of a vehicle body panel weight with a first torsional force stored in a torsion bar within a tilt mechanism that attaches the body panel to the chassis when the body panel is in a first position. The second step is to pivot the body panel about a tilt axis of a tilt mechanism relative to the chassis from the first position to a second position while supporting at least a portion of the body panel weight with the first torsional force stored in the torsion bar. The third step is unloading the torsion bar at the second position, and pivoting the body panel about the tilt axis relative to the chassis from the second position to a third position without loading the torsion bar. At the third position, the body panel weight begins to load the torsion bar again, but in the opposite direction. The fourth step is pivoting the body panel about the tilt axis relative to the chassis from the third position to a fourth position while supporting at least a portion of the body panel weight with a second torsional force generated in the torsion bar as the body panel pivots about the tilt axis from the third position to the fourth position. Hence, the first torsional force has a first rotational direction about the tilt axis that is opposite of a second rotational direction of the second torsional force about the tilt axis. The final step is supporting at least a portion of the body panel weight with the second torsional force stored in the torsion bar when the body panel is in the fourth position. In another embodiment, this method can be reversed by going from the fourth position to a first position. The first position may be a closed position of a truck hood relative to a truck chassis. Correspondingly, the fourth position may be a fully open position of the truck hood relative to the truck chassis.
In accordance with another aspect of the present invention, a method of installing a vehicle body panel on a vehicle chassis comprises the steps of, first, supporting at least a portion of a vehicle body panel weight while positioning the body panel at an installation angle and positioning a tilt mechanism at the installation angle. The tilt mechanism is adapted to pivotably attach the body panel to the chassis, and it has a torsion bar adapted to bias the body panel relative to the chassis about a twist axis of the torsion bar along at least an angular portion of a pivotal range about a tilt axis. The second step is compensating for a lack of angular alignment about the tilt axis between the body panel and the chassis by having the installation angle within a dead band about the tilt axis. The dead band is a specified angular range of the pivotal range about the tilt axis where the torsion bar is unloaded when the body panel is attached to the chassis and pivoting about the tilt axis within the specified angular range. The third step is attaching the body panel to the chassis via the tilt mechanism without loading the torsion bar by having the installation angle within the deadband.